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Use of Acorns for Food in California: Past, Present, Future - by David Bainbridge

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Ever eat an Acorn? Most parts are edible. Okay, that's a take off from Euell Gibbons. Here is a reprint of a doc file by David Bainbridge promoting the usage of various acorns as human food sources and animal fodder. Most may recalled the acorn as an import port of the native American diet, though most likely many have forgotten the art of processing these valuable seeds. Here is an informative paper by Bainbridge on this very important and with climate Change maybe invaluable technical document in identification, collecting, processing and cooking with Oak Acorns.

Use of Acorns for Food in California:
Past, Present, Future

David
A. Bainbridge

Presented at the Symposium on
Multiple-use Management of California's Hardwoods, November 12-14, 1986, San
Luis Obispo, California.2David A. Bainbridge, Dry Lands Research
Institute, University of California, Riverside, CA 92521

Abstract:Acorns
are a neglected food for people, livestock, domestic fowl, and wildlife in
California. Acorns are easy to collect, store, and process. In addition to the
nutritious nut and meal, acorns yield an oil comparable in quality and flavor
with olive oil. The existing acorn market could be greatly expanded and provide
new income for rural people. A serious effort to identify and propagate the
best oak acorn cultivars for these products is long overdue. It is particularly
appropriate for this research to be done in California, which once had an acorn
based economy.

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INTRODUCTION

Acorns have been used as
food by Homo sapiens for thousands of years virtually everywhere oaks are
found. The worldwide destruction of the acorn resource by mismanagement may
well have led to the development of annual plant based agriculture and to
civilization as we know it today (Bohrer, 1972; Bainbridge, 1985b). In Europe,
Asia, North Africa, the Mid-East, and North America, acorns were once a staple
food, (Hedrick, 1919; Loudon, 1844; Brandis, 1972; Lefvebre, 1900; and Bishop,
1891). The Ch'i Min Yao Shu, a Chinese agricultural text from the sixth century
recommends Quercus mongolica as a nut tree (Shen Han, 1982). In Spain and Italy
acorns provided 20 percent of the diet of many people just before the turn of
the Century (Memmo, 1894).

Acorns were perhaps
nowhere more important than in California. For many of the native Californians
acorns made up half of the diet (Heizer and Elsasser, 1980) and the annual
harvest probably exceeded the current California sweet corn harvest, of 60,000
tons. Acorn foods remain on the market not only in Korea, China, and North
Africa, but in most major American cities, at Korean food stores (Wolfert,
1973; Bainbridge, 1985a).

A reevaluation of acorns
and their uses is long overdue. The acorns of all 500 species should be tested.
Although the acorns of some oaks are probably too small or too hard to open for
widespread use many species that can and should be planted for use as food.
They are also valuable feed for domestic animals and birds, and wildlife.

The factors that made
acorns a major food source in California in the past make them attractive
candidates for greater use in the future. They often ripen all at once and are
easy to collect. They store well and were kept by the native Californians for
several years in simple storage bins (Merriam, 1918). They are simple to
prepare, even for the varieties that need to be leached. Although most species
are bland, as are corn and wheat; some have good flavor and could be used in
place of other nuts.

The yield of acorns per
acre compares well with grains. When the long-lived, deep-rooted oaks can reach
sufficient water; acorn production can be very high, with yields of more than
5,280 kg/ha (6,000 pounds/ acre) (Bainbridge, 1986). High acorn yields can be
maintained on hilly lands where annual grain crops cause severe soil erosion
(Bainbridge, 1987a).page 1.

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ACORN
HARVESTING

Harvesting acorns should
be very similar to the harvesting of other commercial nuts such as almonds or
filberts. Wolf (1945) found that it was possible to collect from 110-660 kg
(50-300 lbs) of acorns per hour with very simple hand tools. My own experience
has confirmed these numbers. However, when harvesting small acorns, like Q.
gambelii, in an off year it may be possible to collect only a few pounds per
hour.

ACORN
NUTRITION

The nutritional qualities
of 18 species of acorns are described in Table 1. California's acorns are
described in Table 2.

X-ray
diffraction showed that the structure of acorn starch from Q. mongolica and Q.
crispula fell between that of corn and potatoes. Acorn starch had limited
gelatinization at 61-68oC, with gelatinization of Q. crispula lowest and Q.
mongolica highest (Kim and Lee, 1976).Page 2.

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The amylose
content of acorn starch was 27.1 percent, blue value 0.43 and Aldehyde number
1103 (Chung et al., 1975). Acorns are also good sources of some vitamins, with
5 - 54.8 mg of Vitamin C per 100 gm of raw acorn (Djordjevic, 1954; Minieri,
1954). This compares favorably with the Negev lemon, with 58.1 mg per 100 g.
Acorns are also an excellent source of Vitamin A, with 180 IU per gm in Q.
phellos (King and Titus, 1943). Twenty-seven grams, or less than tenth of pound
of acorns, would meet the suggested daily requirement of 5,000 IU for vitamin
A. This may prove of great benefit in areas of the world where vitamin A
deficiency is common among the poor. Thorough testing of a full range of oak
species and oak processing methods may well discover other species with even
higher levels of these and other vitamins and trace elements.

Acorns include many
essential amino acids, Table 3. (Luk'yanets, 1978; Videl and Varela, 1969).
Testing is needed to establish the amino acid content of the California
species. Minor deficiencies can probably be rectified with complementary
legumes, fish, or meats. When acorns are cooked with ash, to neutralize
bitterness, the acorn foods should also be a good source of calcium. Cooking
with ash may also make more niacin available if the tests Ruttle (1976),
conducted on corn are replicable for acorns. Acorns also supply many trace
elements. It is not at all surprising that acorn-based cultures prospered for
thousands of years with this excellent food base.

Michaux,
1810; Ofcarcik et al., 1971; Smith, 1950; Fray, 1986). Undoubtedly, other
species and varieties are equally sweet and more flavorful. A careful worldwide search
for good cultivars is long overdue because there is hope of finding sweet
acorns even in those species normally considered bitter. Some of these include
the best tasting acorns, with cashew and chocolate overtones.

ACORN
LEACHING

It is also practical to
harvest and use the bitter varieties. The tannins which causes the bitterness
can be leached from acorns or acorn meal with water. Using hot water hastens
the process. Studies at Dong-guk University in Seoul, South Korea showed the
tannin level was reduced from 9 percent to 0.18 percent by leaching, without
loss of essential amino acids, (Kim and Shin, 1975). Virtually all of the
acorns the native Californians used were bitter and were leached with water to
remove the bitterness. They apparently based their acorn preference on oil
content, storability, and flavor rather than sweetness. However, the Cahuilla
people in Southern California remember sweeter acorns from their past (in the
South-Central U.S.) and consider their loss as a fall from grace, like Adam and
Eve's expulsion from the garden (Bainbridge, 1987a).

Native Americans also
sweetened bitter acorns with iron-rich red earth, wood ashes, and other
ingredients to neutralize the acids. Steaming or baking were sufficient for
some acorns (Chestnut, 1974; Kavasch, 1979; and Gifford, 1936).

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by Amber Dusick

COOKING
WITH ACORNS

Acorn meal can be
substituted for corn meal in most recipes (Bainbridge, 1986b). Acorns can also
be used in place of chickpeas, nuts, peanuts, and olives in a variety of
dishes. Acorn meal and acorn pieces are excellent in soups and stews and were
often used that way by native Californians. Acorns can also be treated with
pickle brines or the lye treatment used for olives (Wolf, 1945; Bainbridge,
1986b). Acorns have also been used to make coffee-like drinks (Kavasch, 1979).
The success of the venture depends on the particular acorn and technique used.
Q. muehlenbergii was especially favored for this purpose in the Midwest,
(Ofcarcik et al., 1971). Q. robur and Q. frainetto have been used in Europe
where the resulting drink is referred to as "Eichel kaffee", or acorn
coffee (Sholto Douglas, 1978; Readers Digest, 1984). A similar acorn coffee has
been used in Mexico, (Usher, 1974). Raccahout, a spicy Turkish acorn drink more
like hot chocolate, was included in the Larousse Gastronomique until recently.

ACORN
OIL

Acorns can also be used to
make acorn oil by boiling, crushing, or pressing. Acorn oil has been used as a
cooking oil in Algeria and Morocco (Loudon, 1844; Hedrick, 1919; Smith, 1950).
It was used by the Indians of the eastern U.S. for cooking and as a salve for
burns and injuries (Michaux, 1810; Smith, 1950). Some varieties contain more
than 30 percent oil, equal or greater than the best oil olives ( Wolf, 1945;
Ofcarcik et al., 1971). The quality and flavor of the oil is comparable to
olive oil (Wolf, 1945; Smith, 1950; Bainbridge, 1985a). Table 4 presents
further information on acorn oil.TABLE
4. ACORN OILSpeciesQuercusQuercus5 other OliveCorn agrifolia and ilex species

Page 4.

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Acorn Fodder

ACORNS
AS FODDER

The meal left after
pressing oil can be used for animal feed, but the whole acorns are better. They
have been used for feeding livestock for many thousands of years. Most acorns,
even without leaching, can be fed up to 20 percent of the ration of chickens
(Weingarten, 1958; Boza et al., 1966; Varela et al., 1965; Medina Blanco and
Aparico Macarro, 1965). Acorn fed bear and hog meat were highly valued in the
early days of California settlement. Acorn-fed hogs were especially favored in
Italy (Maymone and Durante, 1943). Leached acorns can be used for 50 percent or
more of the diet, as part of a balanced diet, and may make up 90 percent of the
diet of some California deer herds in the Fall and Winter. In addition, many
oak leaves can be fed to livestock and some were eaten by people (Bainbridge,
1985a). Oaks have been grown and maintained primarily for fodder in a number of
countries. Q. infectoria for example, was favored in Iraq where it was
pollarded for better fodder production (Blakelock, 1950). The tannin in bitter
acorns and leaves of some oaks can cause poisoning in livestock if fed in high
percentage. Range poisoning sometimes occurs when other forage is limited. For
further information on acorn poisoning see (Fowler et al., 1965; Duncan, 1961;
Clarke and Cotchin, 1956; McGowan, 1970; Stober et al., 1976).

ACORN
USE IN THE FUTURE

With a serious oak
selection and breeding effort there is little doubt that oaks that bear early
and have large, sweet acorns could be developed for use in most areas of
California. Most of the oaks hybridize well, so much could be done by careful
breeding. Studies at the University of Utah have demonstrated that the
subgeneras will cross, (Cottam et al., 1982), and successful crossing of good
flavor and sweetness should be feasible. This type of hybridization work is
slow, however, so the rapid development of acorns as a commercial crop will be
more dependent on the selection of the best individuals now growing around the
world. Good flavor and large sizes can probably be combined. I have found
acorns weighing more than 19 gms (Q. chrysolepis) and have been told of even larger
acorns. The recent advances in plant breeding and genetics should reduce the
time required to develop a plum sized, tasty acorn. Plant breeding might also
develop a high yielding, sweet acorn and cork producing tree.

Selection
for high productivity may be important for the development of commercial acorn
orchards. Single trees have been found producing: more than 908 kg (2,000 lbs.)
of acorns, Q. lobata, and consistently several hundred kg (pounds) per year, Q.
garryana, Q. agrifolia, Q. ilex, and mixed stands ( Wolf, 1945; Smith, 1950;
Beck, 1977). Smith (1950) estimated that commercial

Page 5.

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oak
orchards would produce 1,250 kg of acorns per hectare (1,400 pounds/acre)
annually with selected cultivars. I suspect this is a conservative estimate as
natural forest yields of 1,300 - 4,400kg per hectare (1,450 - 5,000 lbs/acre)
have been recorded for a good acorn crop, (Koenig 1979; Wolf, 1945). I have
found up to 5,200 kg/ha (6,000 lb/acre) in a good crop year for Q. kellogii in
the Sierra Nevada and similar yields in the forests of Q. chrysolepis in
Southern California.

The challenge is first to
alert farmers, foresters, and the food industry in California to the potential
use of acorns. The second task is to establish a larger market for wild acorns
(similar to the black walnut business) and acorn products. At the same time
there is a critical need to identify and develop oak cultivars for acorn meal,
nut, and oil production. Equipment for harvesting, hulling, and grinding must
also be evaluated. It is likely that filbert harvesters and hullers will work
but only field trials will confirm this.

Detailed economic analysis
of acorn harvesting and processing in California is also needed. Wolf (1945)
has done the only study of the California acorn business I am aware of and his
results were encouraging. The only modern economic evaluation of acorn
harvesting was done in Spain by de Ursinos et al (1969). They determined that
the acorn harvest for industrial production of meal and oil had been
economically viable when they began their study but was no longer profitable at
the end, because of labor cost increases and the release of wild hogs in the
study forest.

With current California
prices for acorn meal running about $ 0.90/lb wholesale and to more than $30
per gallon for specialty nut oils it seems likely that an entrepreneur could
establish a profitable acorn business. This enterprise will be easier to
establish if processing and palatability tests are conducted by University
researchers. These studies could also refine acorn oil processing techniques
and help develop specialty products that can compete in the marketplace.

From my own experience I would think a
talented cook/marketeer could make an entrance into the market with acorn chips
and crackers or acorn breads and muffins. On a larger scale the market for
acorn flour could be much increased and a market for acorn oil could be
established. An acorn beer or acorn alcohol could also be prepared.

SUMMARY

The acorn was once the
staff of life in most of California and many areas of the world (Bainbridge,
1984; Bainbridge, 1985b; Bainbridge, 1986a). It may become a more common food
in California again. It is a perennial "grain" that can be grown on
arid and semi-arid lands and steep slopes where annual grains would cause
severe environmental degradation.

Further research on acorn
composition (particularly vitamins) and flavor, recipes, processing, and oak
tree management is needed. The hardwoods
program undertaken in 1986 (Passof and Bartolome, 1985) is an excellent
beginning but the resource commitment is small and includes no directives for
acorn research.Material on acorns, acorn recipes, and oaks would be appreciated.

ACKNOWLEDGEMENTS

My special thanks to my
parents, who have helped collect and test acorns; to Norma Kobzina for her help
in the libraries of UC Berkeley; and to Joan Fray and Peg Carkeet for their
support and encouragement in collecting and tasting acorns. The help of Dana
Sowers, John Gibson, and Catherine Gring is also appreciated, and special
thanks to Stanley Scher for his review.

2 comments:

I am very surprised by good taste of coffee from acorns. Recently did this myself how it tastes and it is quite good. I'll take inventory of her home. Interestingly there are several recipes for her http://www.open-youweb.com/how-to-make-acorn-coffee/ but do not know what is the best, maybe preferable to try to do them all. Can someone already knows best?